Field of the Invention
The present invention relates to a sheet handling device, and more particularly to such a device for supplying sheet documents to a determined position and thereafter ejecting said sheet documents from said determined position for example in a copier or the like.
Conventionally such a device has been utilized in an image processing apparatus such as a copier or facsimile device for achieving high-speed and efficient image processing.
As an example, an automatic sheet feeder employed in copiers is designed to feed sheet originals stacked on a table to a determined exposure position and then to advance the sheet originals after exposure in the same direction to an exit tray positioned opposite to said stacking table, or to feed the sheet originals from the stacking table to the exposure position and then back to the stacking table along a transport path of substantially closed loop shape.
However, such a device for ejecting the sheets to an exit tray is associated with the drawbacks that the ejected sheets are stacked in the inverted order and that the sheets have to be manually transferred from the tray to the stacking table in case said sheets are to be fed again.
Also, in a device with a closed loop transport path, the leading ends of the returning sheets may not be aligned at the exit of the stacking table in the case that said sheets are of different sizes, since said sheets return to the stacking table from a direction opposite to said exit. Also the closed loop structure requires that the driving units of the transport system be distributed over the entire apparatus. Furthermore there is required a considerable time from the ejection of a sheet original from the exposure position to the setting of a succeeding sheet original on said exposure position.
In case of producing plural copies from each of plural sheet originals with such an automatic sheet feeder, it has been necessary to continuously effect the copying operations corresponding to the desired number of copies for each transported sheet original, and to sort out the obtained copy sheets after the completion of continuous copying operations for all the sheet originals.
Also certain automatic sheet feeders of closed loop structure are capable of feeding the sheets once returned to the stacking table again to the exposure position. However, the sheet originals returning to the stacking table after exposure operation are simply superposed on the sheet originals remaining on the stacking table and often become undistinguishable from the latter or the number of repeated feedings may become uncertain.